Oracle customers pay handsome fees to attend its OpenWorld conference each year, and many of them felt short-changed Tuesday when Larry Ellison skipped his final keynote to watch an America's Cup sailing race.

Oracle Team USA has staged a thrilling comeback in the competition and will take home the prize if it wins one last race Wednesday against Emirates Team New Zealand. But while that's exciting for Oracle's CEO, some OpenWorld attendees have been less impressed.

He shouldnt have done that, that was my first reaction," said Chris Laxmi, a database administrator who waited in line for 20 minutes to get into the keynote and looks forward to Ellison's keynotes each year. "I'm disappointed."

Attendees still got a keynote, but it was delivered by Executive Vice President of Product Development Thomas Kurian, who was unable to prevent a lot of people from leaving the auditorium when they were told Ellison had cancelled.

Boris Aguirre, a systems integrator and Oracle professional from Ecuador, had stood in line for 30 to 40 minutes. "I felt like the America's Cup thing was more important [to Ellison] than the event," he said. "From the perspective of my clients, I feel it was not good."

Kurian's stand-in keynote was also "not good," Aguirre said. In fact, Kurian was almost boring, he said.

In contrast, Microsoft executives who gave a partner keynote prior to Ellison's scheduled slot stole the show, Aguirre said. "When you show people another company making a very good speech and then Oracle's people tell you, 'Larry's not coming,' it's a double bad impact."

Ellison's no-show drew plenty of reactions on Twitter as well, including some that poked fun.

It wasn't clear how compelling Ellison's speech would have been anyway, since the material Kurian used seemed mostly to concern announcements discussed earlier in the conference.

Ellison might have made the speech if Oracle hadn't staged its comeback. If New Zealand had won the first race Tuesday, the competition would have been over and Ellison could conceivably have made it to the stage on time. But Oracle held on, and the contest will now be decided with a final race Wednesday, wind permitting.

If Oracle wins it will be sweet revenge for Ellison, whose San Francisco home was "flag-bombed" in the early hours last week by a group of New Zealand supporters wearing ninja costumes.

Oracle had other options Tuesday that it didn't take, said analyst Ray Wang of Constellation Research.

"What I would have suggested was broadcast the race live, then have Larry helicopter in and do a live feed of him walking into Moscone, talking about Exadata and how big data helped change the game," Wang said. "That's what he should have done, not leave folks hanging."